We applied the stages-of-change model of Prochaska and DiClemente to the problem of drug use among methadone maintenance patients to examine correlates of different stages of treatment readiness. The 276 subjects were divided into stage categories based on self-reported drug use and questionnaire responses regarding plans to discontinue unauthorized drug use in the future. Confirmatory factor analytic procedures validated four process scales derived from a 60-item questionnaire. Each stage was characterized by a profile of change-process scores largely consistent with predictions, though these scores did not distinguish stages as clearly as has been reported in previous research. Analysis of subject characteristics revealed that those in the Precontemplation stage reported significantly longer treatment tenures than subjects in any other stage besides Maintenance.